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Control Experiments (control + experiment)
Selected AbstractsCognitive flexibility in preschoolers: the role of representation activation and maintenanceDEVELOPMENTAL SCIENCE, Issue 3 2008Nicolas Chevalier Preschoolers' lack of cognitive flexibility has often been attributed to perseverative processing. This study investigates alternative potential sources of difficulty such as deficits in activating previously ignored information and in maintaining currently relevant information. In Experiment 1, a new task tapping attentional switching was designed to isolate the difficulty of overriding an initial representation, that is, perseverative processing (,Perseveration' version), and the difficulty of activating a previously ignored representation, that is, activation deficit (,Activation-deficit' version). Three-year-olds' performance suggested that inflexibility may primarily stem from an activation deficit. Control experiments confirmed that the difficulty of the ,Activation-deficit' version could not be attributed to the effect of attraction to novelty. In Experiment 2, ,distraction' errors, alleged to reflect a failure to maintain a relevant representation, and ,perseverative' errors were distinguished. The results highlighted the important role of representation maintenance in flexibility. The present study indicates that preschoolers' lack of cognitive flexibility is multi-determined and prompts us to reconsider the role of perseveration. [source] Effect of N-fertilization, plant genotype and environmental conditions on nifH gene pools in roots of riceENVIRONMENTAL MICROBIOLOGY, Issue 10 2003Zhiyuan Tan Summary Terminal restriction fragment length polymorphism (T-RFLP) analysis of PCR-amplified nitrogenase gene (nifH) fragments is a rapid technique for profiling of diazotrophic microbial communities without the necessity of cultures for study. Here, we examined the impact of N-fertilization, plant genotype and environmental conditions on diazotrophic microbial populations in association with roots of rice (Oryza species) by T-RFLP community profiling and found marked effects on the composition of the microbial community. We found a rapid change of the diazotrophic population structure within 15 days after application of nitrogen fertilizer and a strong effect of environmental conditions and plant genotype. Control experiments revealed that phylogenetically distantly related nifH genes were proportionately amplified, and that signal strength reflected the relative abundance of nifH genes in the sample within a 10-fold range of template concentrations. These results clearly demonstrated that our T-RFLP method was suitable to reflect compositional differences in the diazotrophic community in a semiquantitative manner and that the diazotrophic rhizosphere communities of rice are not static but presumably rather highly dynamic. [source] Attenuated apoptosis response to Fas-ligand in active ulcerative colitisINFLAMMATORY BOWEL DISEASES, Issue 12 2008Jakob B. Seidelin MD Abstract Background: From mainly carcinoma cell line studies, apoptosis has been thought to play a major role in the pathogenesis of ulcerative colitis (UC). Apoptosis has been suggested to be due to a Fas ligand / Fas receptor interaction, but has never been studied in cells from patients with active UC. The aim was to investigate both the spontaneous and the cell death receptor ligand-induced apoptosis in UC. Methods: Twenty patients with UC and 16 control subjects who underwent routine colonoscopy either for the control or surveillance of their disease or where the diagnosis of irritable bowel syndrome was subsequently reached were included. Cultures of isolated colonic crypts were obtained from biopsies and cultured for 4 to 16 hours with Fas ligand or Fas ligand and costimulation with interferon-, (IFN-,). Control experiments were performed on HT29 cells. Apoptosis was assessed by independent methods. Results: Isolated colonocytes from healthy subjects or patients with remission in UC had a dose-dependent response to Fas ligand. This response was abolished in patients with active UC (P < 0.002), and costimulation with IFN-, did not alter this response. Patients with active UC had an increased apoptosis rate of 9.5% compared with controls (P < 0.05). Conclusions: The current study indicates that colonocytes do not respond to cytokine exposure and inflammation by an increased vulnerability, as previously thought. Colonocytes seem to activate cytoprotective programs in response to inflammation. Apart from supporting the regeneration process during inflammation, this response could additionally cause an increased susceptibility to neoplastic transformation. (Inflamm Bowel Dis 2008) [source] Finding Furfural Hydrogenation Catalysts via Predictive ModellingADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2010Zea Strassberger Abstract We combine multicomponent reactions, catalytic performance studies and predictive modelling to find transfer hydrogenation catalysts. An initial set of 18 ruthenium-carbene complexes were synthesized and screened in the transfer hydrogenation of furfural to furfurol with isopropyl alcohol complexes gave varied yields, from 62% up to >99.9%, with no obvious structure/activity correlations. Control experiments proved that the carbene ligand remains coordinated to the ruthenium centre throughout the reaction. Deuterium-labelling studies showed a secondary isotope effect (kH:kD=1.5). Further mechanistic studies showed that this transfer hydrogenation follows the so-called monohydride pathway. Using these data, we built a predictive model for 13 of the catalysts, based on 2D and 3D molecular descriptors. We tested and validated the model using the remaining five catalysts (cross-validation, R2=0.913). Then, with this model, the conversion and selectivity were predicted for four completely new ruthenium-carbene complexes. These four catalysts were then synthesized and tested. The results were within 3% of the model's predictions, demonstrating the validity and value of predictive modelling in catalyst optimization. [source] Photobleaching of Hypocrellin B and its Butylamino-substituted Derivative in SolutionsPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 2 2001Shangjie Xu ABSTRACT The photobleaching of hypocrellin B (HB) and its derivative butylamino-substituted hypocrellin B (BAHB), both of which are potent sensitizers for photodynamic therapy (PDT), were investigated by studies of absorption spectra and quenching experiments and by the determination of photoproducts. Control experiments indicated that the sensitizer, oxygen and light were essential for the photobleaching of HB and BAHB, which suggested that it was a photodynamic process, e.g. the photobleaching processes of both HB and BAHB were mainly self-sensitized photooxidations. The illumination of HB with visible light in oxygenated nonpolar solvents generated singlet oxygen efficiently [,(1O2) = 0.76] which in turn attacked the sensitizer HB with the subsequent formation of an endoperoxide product. The endoperoxide of HB is unstable at room temperature and undergoes loss of singlet oxygen with regeneration of the parent HB. The singlet oxygen released from the endoperoxide of HB was detected with chemical trapping experiments. The quenching experiments indicated that in increasingly polar solvents the superoxide anion mechanism (type I) as well as the singlet oxygen mechanism (type II) contributed to the photobleaching of HB. The introduction of the electron-donating butylamino group not only enhanced the yield of the superoxide anion generation but also altered the position of attack in the BAHB molecule by the activated oxygen species. No endoperoxide product was observed, and no singlet oxygen released from the photobleaching process of BAHB was detected. The photobleaching process of BAHB was more complex. Both the singlet oxygen and superoxide anion mechanism played important roles in the photobleaching of BAHB in all organic solvent used here, even in aerobic nonpolar solvents such as CHCl3. [source] Intracortical modulation of cortical-bulbar responses for the masseter muscleTHE JOURNAL OF PHYSIOLOGY, Issue 14 2008Enzo Ortu Short interval intracortical inhibition (SICI) and intracortical facilitation (ICF) were evaluated in the masseter muscles of 12 subjects and the cortical silent period (SP) in nine subjects. Motor evoked potentials (MEPs) were recorded from contralateral (cMM) and ipsilateral (iMM) masseters, activated at 10% of maximal voluntary contraction (MVC). Interstimulus intervals (ISIs) were 2 and 3 ms for SICI, 10 and 15 ms for ICF. TMS of the left masseteric cortex induced MEPs that were larger in the cMM than the iMM; stimulation of right masseteric cortex produced a similar asymmetry in response amplitude. SICI was only observed using a CS intensity of 70% AMT and was equal in both cMM and iMM. SICI was stronger at higher TS intensities, was abolished by muscle activation greater than 10% MVC, and was unaffected by coil orientation changes. Control experiments confirmed that SICI was not contaminated by any inhibitory peripheral reflexes. However, ICF could not be obtained because it was masked by bilateral reflex depression of masseter EMG caused by auditory input from the coil discharge. The SP was bilateral and symmetric; its duration ranged from 35 to 70 ms depending on TS intensity and coil orientation. We conclude that SICI is present in the cortical representation of masseter muscles. The similarity of SICI in cMM and iMM suggests either that a single pool of inhibitory interneurons controls ipsi- and contralateral corticotrigeminal projections or that inhibition is directed to bilaterally projecting corticotrigeminal fibres. Finally, the corticotrigeminal projection seems to be weakly influenced by inhibitory interneurons mediating the cortical SP. [source] Exposure of human peripheral blood lymphocytes to electromagnetic fields associated with cellular phones leads to chromosomal instabilityBIOELECTROMAGNETICS, Issue 2 2003Maya Mashevich Abstract Whether exposure to radiation emitted from cellular phones poses a health hazard is at the focus of current debate. We have examined whether in vitro exposure of human peripheral blood lymphocytes (PBL) to continuous 830 MHz electromagnetic fields causes losses and gains of chromosomes (aneuploidy), a major "somatic mutation" leading to genomic instability and thereby to cancer. PBL were irradiated at different average absorption rates (SAR) in the range of 1.6,8.8 W/kg for 72 hr in an exposure system based on a parallel plate resonator at temperatures ranging from 34.5,37.5 °C. The averaged SAR and its distribution in the exposed tissue culture flask were determined by combining measurements and numerical analysis based on a finite element simulation code. A linear increase in chromosome 17 aneuploidy was observed as a function of the SAR value, demonstrating that this radiation has a genotoxic effect. The SAR dependent aneuploidy was accompanied by an abnormal mode of replication of the chromosome 17 region engaged in segregation (repetitive DNA arrays associated with the centromere), suggesting that epigenetic alterations are involved in the SAR dependent genetic toxicity. Control experiments (i.e., without any RF radiation) carried out in the temperature range of 34.5,38.5 °C showed that elevated temperature is not associated with either the genetic or epigenetic alterations observed following RF radiation,the increased levels of aneuploidy and the modification in replication of the centromeric DNA arrays. These findings indicate that the genotoxic effect of the electromagnetic radiation is elicited via a non-thermal pathway. Moreover, the fact that aneuploidy is a phenomenon known to increase the risk for cancer, should be taken into consideration in future evaluation of exposure guidelines. Bioelectromagnetics 24:82,90, 2003. © 2003 Wiley-Liss, Inc. [source] A General Approach to Fabricate Diverse Noble-Metal (Au, Pt, Ag, Pt/Au)/Fe2O3 Hybrid NanomaterialsCHEMISTRY - A EUROPEAN JOURNAL, Issue 27 2010Jun Zhang Dr. Abstract A novel, facile, and general one-pot strategy is explored for the synthesis of diverse noble-metal (Au, Pt, Ag, or Pt/Au)/Fe2O3 hybrid nanoparticles with the assistance of lysine (which is a nontoxic, user friendly amino acid that is compatible with organisms) and without using any other functionalization reagents. Control experiments show that lysine, which contains both amino and carboxylic groups, plays dual and crucial roles as both linker and capping agents in attaching noble metals with a small size and uniform distribution onto an Fe2O3 support. Considering the perfect compatibility of lysine with organism, this approach may find potentials in biochemistry and biological applications. Furthermore, this novel route is also an attractive alternative and supplement to the current methods using a silane coupling agent or polyelectrolyte for preparing hybrid nanomaterials. To demonstrate the usage of such hybrid nanomaterials, a chemical gas sensor has been fabricated from the as-synthesized Au/Fe2O3 nanoparticles and investigated for ethanol detection. Results show that the hybrid sensor exhibits significantly improved sensor performances in terms of high sensitivity, low detection limit, better selectivity, and good reproducibility in comparison with pristine Fe2O3. Most importantly, this general approach can be further employed to fabricate other hybrid nanomaterials based on different support materials. [source] Organocatalytic Asymmetric Mannich Reactions with N -Boc and N -Cbz Protected ,-Amido Sulfones (Boc: tert -Butoxycarbonyl, Cbz: Benzyloxycarbonyl)CHEMISTRY - A EUROPEAN JOURNAL, Issue 29 2007Olindo Marianacci Abstract Different malonates and ,-ketoesters can react with N - tert -butoxycarbonyl- (N -Boc) and N -benzyloxycarbonyl- (N -Cbz) protected ,-amido sulfones in an organocatalytic asymmetric Mannich-type reaction. The reaction makes use of a simple and easily obtained phase-transfer catalyst and proceeds under very mild and user-friendly conditions. The optimised protocol avoids the preparation and the isolation of the relatively unstable N -Boc and N- Cbz imines that are generated in situ from the bench-stable ,-amido sulfones. The corresponding Mannich bases are generally obtained in good yields and enantioselectivities, and can be readily transformed into key compounds, such as optically active ,3 -amino acids in one easy step. Enantioenriched N -Boc and N -Cbz protected ,-amino acids that are suitable for peptide synthesis are also available from the Mannich adducts through simple manipulations. Control experiments showed the dual role of the enolate,catalyst ion pair in this reaction, as well as the crucial role of the presence of water to achieve high enantioselectivities. [source] Ligand-Gated Synthetic Ion ChannelsCHEMISTRY - A EUROPEAN JOURNAL, Issue 22 2005Pinaki Talukdar Abstract Supramolecular ,-stack architecture is fundamental in DNA chemistry but absent in biological and synthetic ion channels and pores. Here, a novel rigid-rod ,-stack architecture is introduced to create synthetic ion channels with characteristics that are at the forefront of rational design, that is, ligand gating by a conformational change of the functional supramolecule. Namely, the intercalation of electron-rich aromatics is designed to untwist inactive electron-poor helical ,-stacks without internal space into open barrel-stave ion channels. Conductance experiments in planar lipid bilayers corroborate results from spherical bilayers and molecular modeling: Highly cooperative and highly selective ligand gating produces small, long-lived, weakly anion selective, ohmic ion channels. Structural studies conducted under conditions relevant for function provide experimental support for helix,barrel transition as origin of ligand gating. Control experiments demonstrate that minor structural changes leading to internal decrowding suffice to cleanly annihilate chiral self-organization and function. [source] Experience with model predictive control in the undergraduate laboratoryCOMPUTER APPLICATIONS IN ENGINEERING EDUCATION, Issue 1 2005Kenneth R. Muske Abstract A model predictive control experiment for an undergraduate senior laboratory course is outlined in this article. The process under study is a continuous stirred-tank heater and the control objective is to control the water temperature in the tank. A discrete, dynamic, physical model of this process is used in the controller. The model predictive control algorithm is a single-move, analytical controller that matches the model predicted temperature to a reference temperature trajectory at a single time in the future. A series of different control experiments using this algorithm are described and examples of each are presented. © 2005 Wiley Periodicals, Inc. Comput Appl Eng Educ 13: 40,47, 2005; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20028 [source] A simple real-time process control experiment using serial communicationCOMPUTER APPLICATIONS IN ENGINEERING EDUCATION, Issue 2 2001Ivo Neitzel Abstract Microcomputers introduced process control to a new era. A simple and didactic experiment, used to control the temperature of an equipment, is described. Features of this experiment include the use of two computers connected by serial ports and allowing students to build the controller and to disturb the process. © 2001 John Wiley & Sons, Inc. Comput Appl Eng Educ 9: 101,104, 2001 [source] Adult gaze influences infant attention and object processing: implications for cognitive neuroscienceEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2005Vincent M. Reid Abstract Infants follow others' gaze toward external objects from early in ontogeny, but whether they use others' gaze in processing information about objects remains unknown. In Experiment 1, 4-month-old infants viewed a video presentation of an adult gazing toward one of two objects. When presented with the same objects alone a second time, infants looked reliably less at the object to which the adult had directly gazed (cued object). This suggests that the uncued object was perceived as more novel than the object previously cued by the adult's gaze. In Experiment 2, adult gaze was not directed towards any object. In this control experiment, infants looked at both objects equally in the test phase. These findings show that adult eye gaze biases infant visual attention and information processing. Implications of the paradigm for cognitive neuroscience are presented and the results are discussed in terms of neural structures and change over ontogeny. [source] Independent on-line control of the two hands during bimanual reachingEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2004Jörn Diedrichsen Abstract Many studies on bimanual coordination have shown that people exhibit a preference for mirror-symmetric movements. We demonstrate that this constraint is absent when bimanual reaching movements are made to visual targets. We investigated the ability of humans to make on-line adjustments during such movements when one or both targets were displaced during the initial phase of the movements. Adjustments were as efficient during bimanual as unimanual movements, even when two adjustments had to be made simultaneously. When one target was displaced in the bimanual condition, the hand reaching to that target adjusted efficiently to the displacement. However, a small transient perturbation in the trajectory of the other hand was also observed. This perturbation was in the same direction as the displacement, rather than in mirror-symmetric direction. A control experiment demonstrated that these perturbations could be elicited by visual information alone, but that they were also influenced by whether an adjustment was required in the trajectory of the other hand. Our results demonstrate near independent control of the two arms during visually guided reaching. The subtle interference observed between the arms reflects interactions between target-related representations in visual coordinates rather than between movement-related representations in joint- or muscle-coordinates. [source] Time-dependent hierarchical organization of spatial working memory: a transcranial magnetic stimulation studyEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 9 2002Thomas Nyffeler The performance of memory-guided saccades with two different delays (3 and 30 s of memorization) was studied in seven healthy subjects. Double-pulse transcranial magnetic stimulation (dTMS) with an interstimulus interval of 100 ms was applied over the right dorsolateral prefrontal cortex (DLPFC) early (1 s after target presentation) and late (28 s after target presentation). Early stimulation significantly increased in both delays the percentage of error in amplitude (PEA) of contralateral memory-guided saccades compared to the control experiment without stimulation. dTMS applied late in the delay had no significant effect on PEA. Furthermore, we found a significantly smaller effect of early stimulation in the long-delay paradigm. These results suggest a time-dependent hierarchical organization of the spatial working memory with a functional dominance of DLPFC during the early memorization, independent from the memorization delay. For a long memorization delay, however, working memory seems to have an additional, DLPFC-independent component. [source] Thermally Responsive Biomineralization on Biodegradable Substrates,ADVANCED FUNCTIONAL MATERIALS, Issue 16 2007J. Shi Abstract Biomineralization offers an elegant example of how nature can design complex, hierarchical, and structurally/morphologically controllable materials. In this work, the surface of bioactive substrates prepared from poly(L -lactic acid) and reinforced with Bioglass are modified by the graft polymerization of poly(N -isopropylacrylamide), (PNIPAAm) after plasma activation. It is found that such treatment, together with temperature, could trigger the formation of apatite on the biodegradable substrate upon immersion in simulated body fluid above the PNIPAAm lower critical solution temperature (LCST); in contrast, no apatite is formed at room temperature. A control experiment on a material that is not subjected to surface treatment does not show any evidence of mineral deposition at the two analyzed temperatures. This "smart" biomineralization concept is combined with patterning methodologies to control the microstructure of the surface onto which PNIPAAm is grafted. In this case, the apatite is formed at 37,°C in the modified regions. We suggest that this concept could be extended in the biomimetic production of other minerals, where it would be triggered by another kind of stimulus (e.g., pH or ionic strength) in substrates with more complex geometries. [source] Design of a near-optimal adaptive filter in digital signal processor for active noise controlINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 1 2008S. M. Yang Abstract Adaptive filter has been applied in adaptive feedback and feedforward control systems, where the filter dimension is often determined by trial-and-error. The controller design based on a near-optimal adaptive filter in digital signal processor (DSP) is developed in this paper for real-time applications. The design integrates the adaptive filter and the experimental design such that their advantages in stability and robustness can be combined. The near-optimal set of controller parameters, including the sampling rate, the dimension of system identification model, the dimension (order) of adaptive controller in the form of an FIR filter, and the convergence rate of adaptation is shown to achieve the best possible system performance. In addition, the sensitivity of each design parameter can be determined by analysis of means and analysis of variance. Effectiveness of the adaptive controller on a DSP is validated by an active noise control experiment. Copyright © 2007 John Wiley & Sons, Ltd. [source] Sensitivity study of the urban heat island intensity to urban characteristicsINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 7 2008R. Hamdi Abstract A detailed urban surface exchange parameterization, implemented in a meso-scale atmospheric model, has been used to study the urban heat island (UHI) intensity during a summer period in the city of Basel, Switzerland. In this urban parameterization, the city is represented as a combination of three urban classes (road, roof and wall), characterized by the size of the street canyon and the building and is thus able to take into account the momentum sink over the entire height of the building, as well as the shadowing and the radiation trapping effects. A control experiment including all the urban parameters describing the city centre of Basel produced a canyon air temperature that compared well with observations. A series of experiments was then conducted in which successively each of the urban parameters characterizing the city centre was changed providing the basis for an assessment of its effect on UHI mitigation. Copyright © 2007 Royal Meteorological Society [source] Synergism of microwave irradiation and enzyme catalysis in synthesis of isoniazidJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 11 2007Ganapati D Yadav Abstract Isoniazid is a useful antitubercular drug widely employed in combination therapy with rifampicin. The synthesis of isoniazid from ethyl isonicotinate and hydrazine hydrate was studied in non-aqueous media via lipase-catalyzed hydrazinolysis under both conventional heating and microwave irradiation by using different supported lipases. Among three different commercial lipases used, namely Novozym 435 (Candida antarctica lipase), Lipozyme RM IM (Rhizomucor miehei lipase) and Lipozyme TL IM (Thermomyces lanuginosus lipase), Novozym 435 was found to be the most effective, with conversion of 54% for equimolar concentrations at 50 °C in 4 h. The rate of reaction as well as final conversion increased synergistically under microwave irradiation in comparison with conventional heating, which showed 36.4% conversion, even after 24 h, for the control experiment. Effects of various process parameters such as speed of agitation, catalyst loading, substrate concentration, product concentration and temperature were studied. A kinetic model is also described. Copyright © 2007 Society of Chemical Industry [source] Effect of inoculation dosing on the composting of source-selected organic fraction of municipal solid wastesJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 3 2006Raquel Barrena Abstract The effects of a commercial inoculum (MicroGest 10X, Brookside Agra L.C.) on the field-scale composting of the source-selected organic fraction of municipal solid wastes (OFMSW) have been studied by following routine parameters of the composting process (temperature, oxygen content and moisture) and biologically-related tests such as the respirometric index and the maturity grade. The inoculum was added to composting piles of OFMSW at different levels: control (no added inoculum), treatment A (105 CFU g,1 of OFMSW), treatment B (106 CFU g,1 of OFMSW) and treatment C (107 CFU g,1 of OFMSW). The inoculum selected produced a significant acceleration of the composting process with high levels of biological activity in the thermophilic phase. In terms of the acceleration of composting and economy the optimal treatment was B, which produced a reduction of approximately half of the total composting time. Treatment C did not improve significantly the results obtained with treatment B, whereas treatment A has little effect on the composting of OFMSW when compared with the control experiment. Respirometric index (determined at 55 °C) and maturity grade appeared to be the most reliable tests to follow the biological activity of the composting of OFMSW. On the other hand, routine parameters such as temperature, oxygen content and moisture showed no significant differences among the different inoculation levels tested in the composting process. Copyright © 2005 Society of Chemical Industry [source] EVIDENCE FOR A SPECIALIZED LOCALIZATION OF THE CHLOROPLAST ATP-SYNTHASE SUBUNITS ,, ,, AND , IN THE EYESPOT APPARATUS OF CHLAMYDOMONAS REINHARDTII (CHLOROPHYCEAE),JOURNAL OF PHYCOLOGY, Issue 2 2007Melanie Schmidt The eyespot apparatus (EA) of Chlamydomonas reinhardtii P. A. Dang. consists of two layers of carotenoid-rich lipid globules subtended by thylakoids. The outermost globule layer is additionally associated with the chloroplast envelope membranes and the plasma membrane. In a recent proteomic approach, we identified 202 proteins from isolated EAs of C. reinhardtii via at least two peptides, including, for example, structural components, signalling-related proteins, and photosynthetic-related membrane proteins. Here, we have analyzed the proteins of the EA with regard to their topological distribution using thermolysin to find out whether the arrangement of globules and membranes provides protection mechanisms for some of them. From about 230 protein spots separated on two-dimensional gels, the majority were degraded by thermolysin. Five major protein spots were protected against the action of this protease. These proteins and some that were degradable were identified by mass spectrometry. Surprisingly, the thermolysin-resistant proteins represented the , and , subunits of the soluble CF1 complex of the chloroplast ATP synthase. Degradable proteins included typical membrane proteins like LHCs, demonstrating that thermolysin is not in general sterically prevented by the EA structure from reaching membrane-associated proteins. A control experiment showed that the CF1 complex of thylakoids is efficiently degraded by thermolysin. Blue native PAGE of thermolysin-treated EAs followed by SDS-PAGE revealed that the , and , subunits are present in conjunction with the , subunit in a thermolysin-resistant complex. These results provide strong evidence that a significant proportion of these ATP-synthase subunits have a specialized localization and function within the EA of C. reinhardtii. [source] Vibration prolongs the cortical silent period in an antagonistic muscleMUSCLE AND NERVE, Issue 6 2009Christian Binder MD Abstract We tested whether the silent period, an indicator of inhibitory neuronal activity, is modulated by muscle vibration. Vibration was applied to the right extensor carpi radialis (ECR) muscle in 17 healthy subjects and, as a control experiment, to the dorsal terminal phalanges in 5 subjects. Data before vibration were compared with those during vibration. The cortical silent period (CSP) was evoked by transcranial magnetic stimuli (TMS) during voluntary wrist flexion or during voluntary wrist extension. TMS-evoked motor potentials (MEPs) of the flexor carpi radialis (FCR) muscle were recorded during muscle relaxation. The mixed nerve silent period (MNSP) was obtained by electrical stimulation of the median nerve during wrist flexion. ECR vibration induced a significant prolongation of the CSP in FCR. CSP increases induced by vibration of the dorsal terminal phalanges were significantly less pronounced. In ECR, the CSP tended to be shortened. MEPs and MNSP remained unchanged. We conclude that vibration enhances inhibitory neuronal properties in a non-vibrated antagonistic muscle, presumably at a supraspinal level. These results may be relevant for the treatment of spasticity of the upper extremity. Muscle Nerve, 2009 [source] Effect of transcranial magnetic stimulation on voluntary activation in patients with quadriceps weaknessMUSCLE AND NERVE, Issue 2 2005Dietmar Urbach MD Abstract Joint disease causes weakness and wasting of adjacent muscles, in part because of inability to fully activate these muscles voluntarily. Previous findings suggest that transcranial magnetic stimulation (TMS) paired with muscle contractions enhances maximal voluntary contraction force (MVC) in healthy subjects by improving voluntary activation (VA). The aim of the present study was to evaluate whether such an effect is also present in subjects suffering from diminished muscle force due to decreased VA. Three single TMS over resting motor threshold were applied in 10 patients with a mean age of 62 years after total-knee arthroplasty either during MVC or during muscle relaxation (control experiment) in a blinded randomized crossover study. MVC and VA were determined using a twitch-interpolation technique at 1, 15, 30, and 60 min after stimulation. There was a significant effect of TMS on MVC if applied in synchrony with muscle contraction, and this persisted for at least 60 min beyond stimulation. In patients suffering from joint disease, TMS might make physiotherapy more effective. Muscle Nerve, 2005 [source] Technical Note: Effect of contact lenses on measurement of the accommodation microfluctuationsOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 1 2008Mhairi Day Abstract Aim:, Dynamic measurement of accommodation in subjects with myopia usually involves recording through soft contact lenses (CLs) to correct the refractive error. Conversely, dynamic accommodation measurement in emmetropic control subjects is generally undertaken without any corrective lenses. The aim of this experiment was to determine whether CL correction affects the measurement of accommodation microfluctuations using infrared refractometry, and whether this needs to be considered in studies which attempt to compare accommodation responses between the two groups. Methods:, Ten young emmetropic subjects viewed a high contrast Maltese cross target monocularly using the right eye at a target vergence of 0 D. The subjects viewed the target under two conditions: with CL condition and without CL condition, where the subjects viewed the target with the eye only. Accommodation responses of the right eye were recorded continuously for 2 min at a sampling rate of 52 Hz using the Shin-Nippon SRW-5000 autorefractor. Results:, No significant difference (two-tailed paired t -test, t9 = ,1.499, p = 0.168) was found in mean accommodation response between the with CL (mean ± S.D. = ,0.02 ± 0.24 D) and without CL conditions (mean ± S.D. = +0.01 ± 0.25 D). No significant (two-tailed paired t -test, t9 = 0.151, p = 0.883) difference in the magnitude of the accommodation microfluctuations was found between the with CL (mean ± S.D. = 0.162 ± 0.04 D) and without CL condition (mean ± S.D. = 0.169 ± 0.04 D). Power spectrum analysis revealed no differences in the characteristics of the microfluctuations waveform between the two conditions. A control experiment carried out on a subgroup of five subjects using a negative (,3 D) CL demonstrated that there was no significant effect of the dioptric power of the CL on the magnitude of the accommodation microfluctuations (anova: F3,15 = 0.254, p = 0.782). Conclusion:, Thin soft CLs do not affect the magnitude or frequency characteristics of accommodation microfluctuations when measured using the Shin-Nippon SRW-5000. [source] Kinetic responses of Dunaliella in moving fluidsBIOTECHNOLOGY & BIOENGINEERING, Issue 1 2010Ahammed Anwar Chengala Abstract The objective of this work was to quantify the kinetic behavior of Dunaliella primolecta (D. primolecta) subjected to controlled fluid flow under laboratory conditions. In situ velocities of D. primolecta were quantified by micron-resolution particle image velocimetry and particle tracking velocimetry. Experiments were performed under a range of velocity gradients and corresponding energy dissipation levels at microscopic scales similar to the energy dissipation levels of natural aquatic ecosystems. An average swimming velocity of D. primolecta in a stagnant fluid was 41,µm/s without a preferential flow direction. In a moving fluid, the sample population velocities of D. primolecta follow a log-normal distribution. The variability of sample population velocities was maximal at the highest fluid flow velocity in the channel. Local fluid velocity gradients inhibited the accrual of D. primolecta by twofold 5 days after the initiation of the experiment in comparison to the non-moving fluid control experiment. Biotechnol. Bioeng. 2010;107: 65,75. © 2010 Wiley Periodicals, Inc. [source] Bioreactor Coupled with Electromagnetic Field Generator: Effects of Extremely Low Frequency Electromagnetic Fields on Ethanol Production by SaccharomycescerevisiaeBIOTECHNOLOGY PROGRESS, Issue 5 2007Victor H. Perez The effect of extremely low frequency (ELF) magnetic fields on ethanol production by Saccharomyces cerevisiae using sugar cane molasses was studied during batch fermentation. The cellular suspension from the fermentor was externally recycled through a stainless steel tube inserted in two magnetic field generators, and consequently, the ethanol production was intensified. Two magnetic field generators were coupled to the bioreactor, which were operated conveniently in simple or combined ways. Therefore, the recycle velocity and intensity of the magnetic field varied in a range of 0.6,1.4 m s,1 and 5,20 mT, respectively. However, under the best conditions with the magnetic field treatment (0.9,1.2 m s,1 and 20 mT plus solenoid), the overall volumetric ethanol productivity was approximately 17% higher than in the control experiment. These results made it possible to verify the effectiveness of the dynamic magnetic treatment since the fermentations with magnetic treatment reached their final stage in less time, i.e., approximately 2 h earlier, when compared with the control experiment. [source] The Weckud Wetch of the Wast: Lexical Adaptation to a Novel AccentCOGNITIVE SCIENCE - A MULTIDISCIPLINARY JOURNAL, Issue 3 2008Jessica Maye Abstract Two experiments investigated the mechanism by which listeners adjust their interpretation of accented speech that is similar to a regional dialect of American English. Only a subset of the vowels of English (the front vowels) were shifted during adaptation, which consisted of listening to a 20-min segment of the "Wizard of Oz." Compared to a baseline (unadapted) condition, listeners showed significant adaptation to the accented speech, as indexed by increased word judgments on a lexical decision task. Adaptation also generalized to test words that had not been presented in the accented passage but that contained the shifted vowels. A control experiment showed that the adaptation effect was specific to the direction of the shift in the vowel space and not to a general relaxation of the criterion for what constitutes a good exemplar of the accented vowel category. Taken together, these results provide evidence for a context-specific vowel adaptation mechanism that enables a listener to adjust to the dialect of a particular talker. [source] Experience with model predictive control in the undergraduate laboratoryCOMPUTER APPLICATIONS IN ENGINEERING EDUCATION, Issue 1 2005Kenneth R. Muske Abstract A model predictive control experiment for an undergraduate senior laboratory course is outlined in this article. The process under study is a continuous stirred-tank heater and the control objective is to control the water temperature in the tank. A discrete, dynamic, physical model of this process is used in the controller. The model predictive control algorithm is a single-move, analytical controller that matches the model predicted temperature to a reference temperature trajectory at a single time in the future. A series of different control experiments using this algorithm are described and examples of each are presented. © 2005 Wiley Periodicals, Inc. Comput Appl Eng Educ 13: 40,47, 2005; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20028 [source] Changes in presumed motor cortical activity during fatiguing muscle contraction in humansACTA PHYSIOLOGICA, Issue 3 2010T. Seifert Abstract Aim:, Changes in sensory information from active muscles accompany fatiguing exercise and the force-generating capacity deteriorates. The central motor commands therefore must adjust depending on the task performed. Muscle potentials evoked by transcranial magnetic stimulation (TMS) change during the course of fatiguing muscle activity, which demonstrates activity changes in cortical or spinal networks during fatiguing exercise. Here, we investigate cortical mechanisms that are actively involved in driving the contracting muscles. Methods:, During a sustained submaximal contraction (30% of maximal voluntary contraction) of the elbow flexor muscles we applied TMS over the motor cortex. At an intensity below motor threshold, TMS reduced the ongoing muscle activity in biceps brachii. This reduction appears as a suppression at short latency of the stimulus-triggered average of rectified electromyographic (EMG) activity. The magnitude of the suppression was evaluated relative to the mean EMG activity during the 50 ms prior to the cortical stimulus. Results:, During the first 2 min of the fatiguing muscle contraction the suppression was 10 ± 0.9% of the ongoing EMG activity. At 2 min prior to task failure the suppression had reached 16 ± 2.1%. In control experiments without fatigue we did not find a similar increase in suppression with increasing levels of ongoing EMG activity. Conclusion:, Using a form of TMS which reduces cortical output to motor neurones (and disfacilitates them), this study suggests that neuromuscular fatigue increases this disfacilitatory effect. This finding is consistent with an increase in the excitability of inhibitory circuits controlling corticospinal output. [source] Combined effects of discharge, turbidity, and pesticides on mayfly behavior: Experimental evaluation of spray-drift and runoff scenariosENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2005James M. Dabrowski Abstract The effects of the pyrethroid-insecticide cypermethrin (CYP), increased flow speed (Flow), and increased suspended particles (Part) on drift behavior and activity of mayfly nymphs (Baetis harrisoni) were investigated both individually and in combination in a laboratory stream microcosm. Spray-drift trials were performed by exposing the nymphs to 1 ,g/L of CYP. During runoff trials (CYP × Part), contaminated sediment containing 2,000 ,g/kg of CYP was introduced to the microcosm at a concentration of 500 mg/L. Both trials were carried out under high-flow (CYP × Flow and CYP × Part × Flow) and low-flow (CYP and CYP × Part) conditions, and for all cases, control experiments were performed. Drift rate, drift density (for any treatments with increased flow), and activity were used as behavioral endpoints. Multifactorial analysis of variance shows that CYP exposure significantly increased the drift, whereas Part and Flow trials significantly decreased the drift (p < 0.05). In addition, activity decreased significantly under high-flow conditions. The CYP × Part and CYP × Flow treatments resulted in increased drift rate and drift density, respectively, whereas Part × Flow and CYP × Part × Flow treatments resulted in decreased drift density. The CYP × Part and CYP × Flow trials had a significant antagonistic, interactive effect on drift rate and drift density, respectively, with measured levels being lower than expected levels. The reduction in bioavailability of CYP in the presence of increased flow and sediment levels suggests that mayflies are more likely to be affected by spray-drift exposure (CYP) than by runoff exposure (CYP × Part × Flow). Results indicate that mayflies reacted actively in response to flow conditions and passively in response to pesticide exposure. [source] | |||||||||||||||||||||||||||||||||||||||||||